Failure in the form of stress corrosion cracking has occurred on the SS304 lance tube soot blower. The hardness test showed high value for the area close to the failed region. The SEM test showed formation of heterogonous and porosity film on the surface. XRD indicated that the oxides determined were Fe2O3 and Fe3O4. Metallographic of the lance tube revealed pitting as the stress concentrator. Pitting is caused by chloride (as chlorine) and SO2− from the flue gas. SO2− reacts with water to form acidic sodium bisulfate (NaHSO4). Stress is generated from exposure of lance tube parts to high and low temperature during its service.
- Sodium bisulfate
- Stress corrosion cracking